Why? They are more difficult to shoot for beginners, the sights, in general suck, the recoil on some is no fun with full power loads, shall I continue? The J-frame is an excellent gun, I own several, but it’s not really a beginners/newbie gun.
Agreed. For a 5-shot revolver, I would recommend the LCR in .38spl or .357. 6-shot, I'd go K-frame snubby.
That being said, I think the OP is looking for a semi-auto, so I still think 9mm is probably one of the best calibers as far as affordability and "stopping power".